From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB74FC433EF for ; Tue, 11 Jan 2022 03:28:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346709AbiAKD2S (ORCPT ); Mon, 10 Jan 2022 22:28:18 -0500 Received: from mga02.intel.com ([134.134.136.20]:46844 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236937AbiAKD2S (ORCPT ); Mon, 10 Jan 2022 22:28:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1641871697; x=1673407697; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=W2adCTRLvv38iA/+8u7WVqn7sQB+rsB9p8Kv8IHLqYI=; b=aE14dM2IyXrT5c4vz4Rl6ysLGMbQO1vasiU6ztKEk8bUu0o9IPHWl96A P6l1nDJWMP3hctyCcN754NulE1yzxm0u8ycSgP+g3BMf+TkhZ5nVK2m9/ t17uaSjFQb4PWyFW7WkaSs7Uh09ixIu5DO/sMWmPuaqFOAQdp9Ik5BtDZ O4TtDp/lQ/G9DRci/09YSnf4d8XmbzMHHlVs5N0qBfldM59IbsNkwqn2g pmP+3CGsjrdaURHjdZTnLo1FSBUkyGDutWoBW6cHMQl1zcd9y5nVtjO97 CdAgQ/215J3gJ5F+AO0QHrJ7/H4oMIItL4mV/a0IIl9KdVGbivKY6EBou w==; X-IronPort-AV: E=McAfee;i="6200,9189,10223"; a="230734420" X-IronPort-AV: E=Sophos;i="5.88,278,1635231600"; d="scan'208";a="230734420" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jan 2022 19:28:17 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,278,1635231600"; d="scan'208";a="528547093" Received: from ipu5-build.bj.intel.com (HELO [10.238.232.188]) ([10.238.232.188]) by orsmga008.jf.intel.com with ESMTP; 10 Jan 2022 19:28:15 -0800 Subject: Re: [PATCH] media: ov5675: use group write to update digital gain To: Sakari Ailus , "Cao, Bingbu" Cc: "linux-media@vger.kernel.org" , "Tu, ShawnX" , "senozhatsky@chromium.org" , "tfiga@chromium.org" , "Yeh, Andy" References: <1640768259-18070-1-git-send-email-bingbu.cao@intel.com> From: Bingbu Cao Message-ID: <593d842c-2f8a-d4fd-3f31-feca1fd4cf31@linux.intel.com> Date: Tue, 11 Jan 2022 11:22:26 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 1/10/22 7:32 PM, Sakari Ailus wrote: > On Wed, Dec 29, 2021 at 10:00:43AM +0000, Cao, Bingbu wrote: >> Hi Sakari, >> >> Thanks for your review. >> >> ________________________ >> BRs, >> Bingbu Cao >> >>> -----Original Message----- >>> From: Sakari Ailus >>> Sent: Wednesday, December 29, 2021 5:42 PM >>> To: Cao, Bingbu >>> Cc: linux-media@vger.kernel.org; Tu, ShawnX ; >>> senozhatsky@chromium.org; tfiga@chromium.org; bingbu.cao@linux.intel.com; >>> Yeh, Andy >>> Subject: Re: [PATCH] media: ov5675: use group write to update digital >>> gain >>> >>> Hi Bingbu, >>> >>> On Wed, Dec 29, 2021 at 04:57:39PM +0800, Bingbu Cao wrote: >>>> MWB gain register are used to set gain for each mwb channel mannually. >>>> However, it will involve some artifacts at low light environment as >>>> gain cannot be applied to each channel synchronously. Update the >>>> driver to use group write for digital gain to make the sure RGB >>>> digital gain be applied together at frame boundary. >>> >>> How about the analogue gain and exposure time? >>> >>> Shouldn't they be applied similarly as well? Adding two more writes >>> increases the probability of missing a frame there. >> >> We did not meet issue related to analog gain as the it was applied by only >> 1 reg write, it looks like same issue we found on ov8856, changing to set >> digital gain by only 1 global gain write will fix the problem. > > That device is different in its support for global digital gain. This patch > sets the gain for each component separately. > > Adding more writes on a given frame increases the probability of slipping > to the following frame. Doing the exposure and gain updates in the same > group write would alleviate that a little. Sakari, It is feasible to put the exposure and gain update in a same group, however, lunching the group at different time may increase the probability of slipping as well. What do you think? > >> >>> >>> This is of course a trick since the control framework doesn't really >>> support this, but I think this support should be added. >>> >>> -- >>> Regards, >>> >>> Sakari Ailus > -- Best regards, Bingbu Cao